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| 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | |
| 2 // Use of this source code is governed by a BSD-style license that can be | |
| 3 // found in the LICENSE file. | |
| 4 | |
| 5 #include "sync/util/nigori.h" | |
| 6 | |
| 7 #include <stdint.h> | |
| 8 | |
| 9 #include <sstream> | |
| 10 #include <vector> | |
| 11 | |
| 12 #include "base/base64.h" | |
| 13 #include "base/logging.h" | |
| 14 #include "base/strings/string_util.h" | |
| 15 #include "base/sys_byteorder.h" | |
| 16 #include "crypto/encryptor.h" | |
| 17 #include "crypto/hmac.h" | |
| 18 #include "crypto/random.h" | |
| 19 #include "crypto/symmetric_key.h" | |
| 20 | |
| 21 using base::Base64Encode; | |
| 22 using base::Base64Decode; | |
| 23 using crypto::Encryptor; | |
| 24 using crypto::HMAC; | |
| 25 using crypto::SymmetricKey; | |
| 26 | |
| 27 namespace syncer { | |
| 28 | |
| 29 // NigoriStream simplifies the concatenation operation of the Nigori protocol. | |
| 30 class NigoriStream { | |
| 31 public: | |
| 32 // Append the big-endian representation of the length of |value| with 32 bits, | |
| 33 // followed by |value| itself to the stream. | |
| 34 NigoriStream& operator<<(const std::string& value) { | |
| 35 uint32_t size = base::HostToNet32(value.size()); | |
| 36 | |
| 37 stream_.write(reinterpret_cast<char*>(&size), sizeof(uint32_t)); | |
| 38 stream_ << value; | |
| 39 return *this; | |
| 40 } | |
| 41 | |
| 42 // Append the big-endian representation of the length of |type| with 32 bits, | |
| 43 // followed by the big-endian representation of the value of |type|, with 32 | |
| 44 // bits, to the stream. | |
| 45 NigoriStream& operator<<(const Nigori::Type type) { | |
| 46 uint32_t size = base::HostToNet32(sizeof(uint32_t)); | |
| 47 stream_.write(reinterpret_cast<char*>(&size), sizeof(uint32_t)); | |
| 48 uint32_t value = base::HostToNet32(type); | |
| 49 stream_.write(reinterpret_cast<char*>(&value), sizeof(uint32_t)); | |
| 50 return *this; | |
| 51 } | |
| 52 | |
| 53 std::string str() { | |
| 54 return stream_.str(); | |
| 55 } | |
| 56 | |
| 57 private: | |
| 58 std::ostringstream stream_; | |
| 59 }; | |
| 60 | |
| 61 // static | |
| 62 const char Nigori::kSaltSalt[] = "saltsalt"; | |
| 63 | |
| 64 Nigori::Nigori() { | |
| 65 } | |
| 66 | |
| 67 Nigori::~Nigori() { | |
| 68 } | |
| 69 | |
| 70 bool Nigori::InitByDerivation(const std::string& hostname, | |
| 71 const std::string& username, | |
| 72 const std::string& password) { | |
| 73 NigoriStream salt_password; | |
| 74 salt_password << username << hostname; | |
| 75 | |
| 76 // Suser = PBKDF2(Username || Servername, "saltsalt", Nsalt, 8) | |
| 77 std::unique_ptr<SymmetricKey> user_salt(SymmetricKey::DeriveKeyFromPassword( | |
| 78 SymmetricKey::HMAC_SHA1, salt_password.str(), kSaltSalt, kSaltIterations, | |
| 79 kSaltKeySizeInBits)); | |
| 80 DCHECK(user_salt); | |
| 81 | |
| 82 std::string raw_user_salt; | |
| 83 if (!user_salt->GetRawKey(&raw_user_salt)) | |
| 84 return false; | |
| 85 | |
| 86 // Kuser = PBKDF2(P, Suser, Nuser, 16) | |
| 87 user_key_ = SymmetricKey::DeriveKeyFromPassword( | |
| 88 SymmetricKey::AES, password, raw_user_salt, kUserIterations, | |
| 89 kDerivedKeySizeInBits); | |
| 90 DCHECK(user_key_); | |
| 91 | |
| 92 // Kenc = PBKDF2(P, Suser, Nenc, 16) | |
| 93 encryption_key_ = SymmetricKey::DeriveKeyFromPassword( | |
| 94 SymmetricKey::AES, password, raw_user_salt, kEncryptionIterations, | |
| 95 kDerivedKeySizeInBits); | |
| 96 DCHECK(encryption_key_); | |
| 97 | |
| 98 // Kmac = PBKDF2(P, Suser, Nmac, 16) | |
| 99 mac_key_ = SymmetricKey::DeriveKeyFromPassword( | |
| 100 SymmetricKey::HMAC_SHA1, password, raw_user_salt, kSigningIterations, | |
| 101 kDerivedKeySizeInBits); | |
| 102 DCHECK(mac_key_); | |
| 103 | |
| 104 return user_key_ && encryption_key_ && mac_key_; | |
| 105 } | |
| 106 | |
| 107 bool Nigori::InitByImport(const std::string& user_key, | |
| 108 const std::string& encryption_key, | |
| 109 const std::string& mac_key) { | |
| 110 user_key_ = SymmetricKey::Import(SymmetricKey::AES, user_key); | |
| 111 DCHECK(user_key_); | |
| 112 | |
| 113 encryption_key_ = SymmetricKey::Import(SymmetricKey::AES, encryption_key); | |
| 114 DCHECK(encryption_key_); | |
| 115 | |
| 116 mac_key_ = SymmetricKey::Import(SymmetricKey::HMAC_SHA1, mac_key); | |
| 117 DCHECK(mac_key_); | |
| 118 | |
| 119 return user_key_ && encryption_key_ && mac_key_; | |
| 120 } | |
| 121 | |
| 122 // Permute[Kenc,Kmac](type || name) | |
| 123 bool Nigori::Permute(Type type, const std::string& name, | |
| 124 std::string* permuted) const { | |
| 125 DCHECK_LT(0U, name.size()); | |
| 126 | |
| 127 NigoriStream plaintext; | |
| 128 plaintext << type << name; | |
| 129 | |
| 130 Encryptor encryptor; | |
| 131 if (!encryptor.Init(encryption_key_.get(), Encryptor::CBC, | |
| 132 std::string(kIvSize, 0))) | |
| 133 return false; | |
| 134 | |
| 135 std::string ciphertext; | |
| 136 if (!encryptor.Encrypt(plaintext.str(), &ciphertext)) | |
| 137 return false; | |
| 138 | |
| 139 std::string raw_mac_key; | |
| 140 if (!mac_key_->GetRawKey(&raw_mac_key)) | |
| 141 return false; | |
| 142 | |
| 143 HMAC hmac(HMAC::SHA256); | |
| 144 if (!hmac.Init(raw_mac_key)) | |
| 145 return false; | |
| 146 | |
| 147 std::vector<unsigned char> hash(kHashSize); | |
| 148 if (!hmac.Sign(ciphertext, &hash[0], hash.size())) | |
| 149 return false; | |
| 150 | |
| 151 std::string output; | |
| 152 output.assign(ciphertext); | |
| 153 output.append(hash.begin(), hash.end()); | |
| 154 | |
| 155 Base64Encode(output, permuted); | |
| 156 return true; | |
| 157 } | |
| 158 | |
| 159 // Enc[Kenc,Kmac](value) | |
| 160 bool Nigori::Encrypt(const std::string& value, std::string* encrypted) const { | |
| 161 if (0U >= value.size()) | |
| 162 return false; | |
| 163 | |
| 164 std::string iv; | |
| 165 crypto::RandBytes(base::WriteInto(&iv, kIvSize + 1), kIvSize); | |
| 166 | |
| 167 Encryptor encryptor; | |
| 168 if (!encryptor.Init(encryption_key_.get(), Encryptor::CBC, iv)) | |
| 169 return false; | |
| 170 | |
| 171 std::string ciphertext; | |
| 172 if (!encryptor.Encrypt(value, &ciphertext)) | |
| 173 return false; | |
| 174 | |
| 175 std::string raw_mac_key; | |
| 176 if (!mac_key_->GetRawKey(&raw_mac_key)) | |
| 177 return false; | |
| 178 | |
| 179 HMAC hmac(HMAC::SHA256); | |
| 180 if (!hmac.Init(raw_mac_key)) | |
| 181 return false; | |
| 182 | |
| 183 std::vector<unsigned char> hash(kHashSize); | |
| 184 if (!hmac.Sign(ciphertext, &hash[0], hash.size())) | |
| 185 return false; | |
| 186 | |
| 187 std::string output; | |
| 188 output.assign(iv); | |
| 189 output.append(ciphertext); | |
| 190 output.append(hash.begin(), hash.end()); | |
| 191 | |
| 192 Base64Encode(output, encrypted); | |
| 193 return true; | |
| 194 } | |
| 195 | |
| 196 bool Nigori::Decrypt(const std::string& encrypted, std::string* value) const { | |
| 197 std::string input; | |
| 198 if (!Base64Decode(encrypted, &input)) | |
| 199 return false; | |
| 200 | |
| 201 if (input.size() < kIvSize * 2 + kHashSize) | |
| 202 return false; | |
| 203 | |
| 204 // The input is: | |
| 205 // * iv (16 bytes) | |
| 206 // * ciphertext (multiple of 16 bytes) | |
| 207 // * hash (32 bytes) | |
| 208 std::string iv(input.substr(0, kIvSize)); | |
| 209 std::string ciphertext(input.substr(kIvSize, | |
| 210 input.size() - (kIvSize + kHashSize))); | |
| 211 std::string hash(input.substr(input.size() - kHashSize, kHashSize)); | |
| 212 | |
| 213 std::string raw_mac_key; | |
| 214 if (!mac_key_->GetRawKey(&raw_mac_key)) | |
| 215 return false; | |
| 216 | |
| 217 HMAC hmac(HMAC::SHA256); | |
| 218 if (!hmac.Init(raw_mac_key)) | |
| 219 return false; | |
| 220 | |
| 221 std::vector<unsigned char> expected(kHashSize); | |
| 222 if (!hmac.Sign(ciphertext, &expected[0], expected.size())) | |
| 223 return false; | |
| 224 | |
| 225 if (hash.compare(0, hash.size(), | |
| 226 reinterpret_cast<char *>(&expected[0]), | |
| 227 expected.size())) | |
| 228 return false; | |
| 229 | |
| 230 Encryptor encryptor; | |
| 231 if (!encryptor.Init(encryption_key_.get(), Encryptor::CBC, iv)) | |
| 232 return false; | |
| 233 | |
| 234 if (!encryptor.Decrypt(ciphertext, value)) | |
| 235 return false; | |
| 236 | |
| 237 return true; | |
| 238 } | |
| 239 | |
| 240 bool Nigori::ExportKeys(std::string* user_key, | |
| 241 std::string* encryption_key, | |
| 242 std::string* mac_key) const { | |
| 243 DCHECK(user_key); | |
| 244 DCHECK(encryption_key); | |
| 245 DCHECK(mac_key); | |
| 246 | |
| 247 return user_key_->GetRawKey(user_key) && | |
| 248 encryption_key_->GetRawKey(encryption_key) && | |
| 249 mac_key_->GetRawKey(mac_key); | |
| 250 } | |
| 251 | |
| 252 } // namespace syncer | |
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